title: Two-photon fluorescence diagnostics of femtosecond laser tweezers.
abstract: We show how two-photon fluorescence signal can be used as an effective detection scheme for trapping particles of any size in comparison to methods using back-scattered light. Development of such a diagnostic scheme allows us a direct observation of trapping a single nanoparticle, which shows new directions to spectroscopy at the single-molecule level in solution.
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Kanpur, Kanpur 208 016, India.
authors.forename: Arijit
authors.initials: A
authors.lastname: Kumar De
authors.forename: Debjit
authors.initials: D
authors.lastname: Roy
authors.forename: Debabrata
authors.initials: D
authors.lastname: Goswami
keywords: Back scattered light; femtosecond laser pulses; optical tweezers; sub-diffraction scale trapping; two-photon fluorescence